Shoe-box sized device for rural microgrids

By Tereza Pultarova

Published Monday, June 1, 2015

Massachusetts Institute of Technology researchers have developed a simple power management system that would allow people in remote villages in developing countries to share electricity by creating local micro-grids.

The device would allow wealthier villagers owning solar power generators to sell off excess energy to their neighbours who have no access to electricity at all. The device could greatly improve access to modern technology for the 1.3 billion people around the world currently estimated to live completely without electricity.

The device, the size of a shoe box, regulates how electricity from solar panels or other independent sources gets directed for immediate use to either directly power lights or mobile phones or to charge batteries for later use.

At the same time, the system monitors how much power is going to each user, providing a record that can be used for billing without the need for individual meters.

Unlike most electricity grids, the MIT-developed device uses direct current (DC) instead of alternating current (AC). The team says that using DC simplifies the set-up, lowers costs and improves safety of operation.

In fact, most applications foreseen to benefit from the microgrids, such as lighting, phone charging and fans, require DC and would need the current to be converted back if AC was used.

Operating at less than 50 volts, the systems are not capable of delivering life-threatening shocks even if wiring gets damaged and people are accidentally exposed to bare wires, the researchers say.

Test installations will take place in two villages in the Jamshedpur area in northeastern India — one of which has no outside power source at all, and one of which is connected to the grid, but gets only intermittent access, averaging two to three hours of electricity a day.

Unlike typical solar installations in the area, where every lamp, fan, or charger is hard-wired to the system, the MIT system will allow for flexibility in adding or removing extra generators as well as devices.

The team says it would cost local villagers $2 to $5 a month to purchase power, which is less than they currently spend on candles and kerosene for lighting.

The system may as well provide an incentive for those wealthier villagers who may be considering acquiring solar generators but could be put off by the cost. By selling excess power to neighbours, the financial burden will be largely reduced.

Phone charging is one high-demand service that would be met by such a system. Mobile phone services are common in India and other developing nations, but people often have to travel to a nearby city, or pay high prices locally, to charge their phones. In addition, the solar power would enable them to use electric fans, a serious need in this very hot region.